Instrument and Instrument Configuration Restrictions

At each Gemini telescope, instruments are mounted at the Cassegrain focus on the
instrument support structure (ISS). A science fold mirror mounted inside the ISS can be rotated to send the light from the telescope to any of four side-looking ports, or can be retracted so that the light goes to the up-looking port. At each site, the calibration unit and the Adaptive Optics system use two of the side ports, leaving two side-looking and one uplooking port for other instrumentation. As more than three instruments are offered each semester, instrument swaps will be required and not all instruments will be available for the entire semester. Instrument swaps will be driven by demand and scheduled to minimize impact on the queue. Certain targets or entire programs may not be
feasible once the final schedule is determined, at ITAC or thereafter.
If an instrument is requested for less than 6% of the Bands 1+2 time, the Observatory
reserves the right to limit the RA range available to programs, or to not schedule the instrument.
Changes to the instrument mounting are not permitted during
classical runs.

Non-Sidereal Targets

Non-sidereal targets can have a broader range in RA than indicated in the Tables below due to, for example, the need to observe comets relatively close to the Sun. The ephemeris for any submitted target however must include a position that is accessible between evening and morning twilight at some point in the semester. For rapidly moving targets PIs should specify in the proposal when the target is accessible, and the coordinates of the target at that time, so that the observation can be checked for feasibility.

Gemini North Instrument Availability and Target Accessibility

All instruments are restricted for sky visibility as described in the Table and Figure below. In addition:

GNIRS may be removed from the telescope in July for a lens replacement. Investigators with
targets at RA 21 to 01 hours should therefore have backup targets available.

The Laser Guide Star (LGS) system
must be used at or above 40 degrees elevation. How
this translates into RA and dec restrictions is indicated in the Table.

Accessible

Restricted**

Inaccessible

Declination,
non-LGS

-30d to +73d

-37d to -30d,
+73d to +90d

< -37d

Declination,
LGS

-22d to +65d

-27d to -22d,
+65d to +68d

< -27d and > +68d

Right Ascension,
non-LGS

7h to 22h

4h to 7h,
22h to 1h

1h to 4h

Right Ascension,
LGS

8h to 21h

5h to 8h,
21h to 0h

0h to 5h

**Due to limited sky availability during the semester, GMOS MOS programs requiring pre-imaging should not have targets in this region, and other programs
with targets in this region should not require a large amount of time, or have strict timing or observing
constraints.

Gemini South Instrument Availability and Target Accessibility

All instruments are restricted for sky visibility as described in the Table and Figure below. In addition:

GMOS-South may not be available between March and April for a CCD upgrade. The amount of time at RA 7h to 11h will therefore be limited, and investigators should indicate in the technical case of their proposal if alternate targets are available.

Observations using GeMS are restricted to greater than 45 degrees elevation. How
this translates into RA and dec restrictions is indicated in the Table.

Accessible

Restricted**

Inaccessible

Declination

-87d to +22d

-90d to -87d,
+22d to +28d

> +28d

Declination,
GSAOI + GeMS

-70d to +10d

-75d to -70d,
+10d to +15d

< -75d and > +15d

Right Ascension

7h to 23h

5h to 7h,
23h to 2h

2h to 5h

Right Ascension,
GSAOI + GeMS

8h to 22h

6h to 8h,
22h to 1h

1h to 6h

**Due to limited sky availability during the semester, GMOS MOS programs requiring pre-imaging should not have targets in this region, and other programs
with targets in this region should not require a large amount of time, or have strict timing or observing
constraints.

Graphical Illustration

Figure 1: Schematic representation of target accessibility at
Gemini North during semester 2014A. Green regions offer unrestricted
access, red regions are inaccessible.
Hatched areas indicate the more restricted LGS regions. The yellow region is possible, but restricted.
See text, and values in the Gemini North Table above.

Figure 2: Schematic representation of target accessibility at Gemini South during semester 2013B.
Green regions offer unrestricted access, red regions are inaccessible. Hatched areas indicate the more restricted GeMS regions. The yellow region is possible, but restricted. See text, and values in the Gemini South Table above.